sedimentary

Porous limestone (likely fossiliferous)

Calcite-rich limestone, primarily calcium carbonate (CaCO₃)

AI-generated identification · may be incorrect

Pale tan, rough and porous, with irregular cavities and possible fossil fragments. Calcite has Mohs hardness 3, vitreous-to-dull luster, and trigonal crystal structure; the rock itself may fizz in dilute acid.

Identified October 6, 2026More sedimentary →

Explore Porous limestone (likely fossiliferous) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when carbonate mud, shell fragments, or other calcite-rich material accumulates and lithifies in marine or lake environments. The image alone cannot establish its age.

Uses & applications

Limestone is used in cement and lime production, building stone, and aggregate; this small rough specimen is mainly suitable for collecting or study.

Geological facts

Many limestones contain visible shell or fossil debris, though the texture here is not clear enough to identify a fossil confidently.

Field identification & locations

Look for pale color, porous or granular texture, and vigorous fizzing with dilute hydrochloric acid. Limestone occurs widely in sedimentary basins worldwide.